Brake



Nov. 22, 1938. H. G. AX TM ANN, 2,137,522

BRAKE Original Filed Ja r z. 25, 1934 s Sheets-Sheet 1 INVENTORL P01 0 6. Ax r/vA/v A TTORNEY Nov. 22, 1938. H. G. AXTMANN 2,137,522

BRAKE Original Fil ed Jan. 25, 1934 5 Sheets-Sheet 2 2 INVENTOR- l/q/Paw 6. AXT/VA/VN BY I ATTORNEY Nov. 22, 1938. G AXTMANN 2,137,522

BRAKE Original Filed Jan. 25, 1934 3 Sheets-Sheet 5 INVENTbR: 6/9xT/vA/wv ATTORNEY Patented Nov. 22, 1938 j LUNITED STATES PATENT OFFICE I BRAKE Harold G. Axtmann, Dearborn, Mich.,assignor to' Bendix Aviation Corporation, South Bend, Ind.,

. a corporation of Delaware Divided and this application August 10, 1936, Serial No. 95,254

6 Claims.

This invention relates to brakes, and is illustratedas embodied in an internal expandin brake for an automobile wheel.

An object'of the invention is to provide actuating means for a brake of the shiftable anchorage type arranged to act substantially uniformly in forward and'reverse braking. To this end there may be a part mounted on the brake anchor, arranged between the ends of the shoes, and which acts ono ne of the shoes at one side of the anchor, and to which is operatively connected a lever or the like acting on the other shoe at the other side of the anchor. The connections, as explained below, are preferably arranged to give substantially equal braking action.

Various features of novelty are embodied in the specific constructions and arrangements of parts of the several embodiments described below. These and other features of the invention will'be apparent from the following description of the illustrative embodiments shown in the accompanying drawings, in which:

Figure'l is a vertical section through a brake embodying one form of the invention, in a plane just inside the head of the brake drum, and showing the friction shoes in side elevation;

Figure 2 is a similar view of the same brake, but showing only the upper part of the brake, and showing the shoes applied against the drum, with the vehicle moving forward;

Figure 3 is a perspective view of part of the applying means of the brake of Figure l;

. Figures 4, and 6 are partial sections, corresponding to the upper part of Figure 1 but on a larger scale, showing different modified arrangements of the applying means;

Figure 7 is a perspective view of part of the applying means of Figure 6-;

Figure 8 is a partial section corresponding to Figures 4-6, but showing another modification of the applying means;

Figure 9 is a partial perspective of the applying means of Figure 8, with the brake shoes removed;

and

Figure is a partial section corresponding to Figures 4-6, but showing another modification of the applying means.

The brake illustrated in Figures 1, 2 and 3 comprises in combination with the drum 44 and the backing plate 46 friction means such as a pair of floating shoes I96 having a floating adjustable connection including a rotatable member I98, yieldingly locked by a spring 2% connecting the shoes, and having a smooth left end journaled in a socket 202 notched to embrace the end against an anchor or post 208 arranged between the unconnected ends of the shoes, while an inclined-auxiliaryreturn spring 2l0 urges one of the shoes against an adjustable" eccentric stop 2 l2.

The brake is applied by a lever 2l4, connected to the end of the corresponding cable 50, and which has a thrust lug 2|6 wedgingly engaging the'end ofthe left-hand shoe. The lever H4 is connected by a pivot 2l8 with a member 220 the back of which is shown in detail in Figure 3, and which is pivoted on the anchor post 208.

The member 220 has a lug portion 222, shown surrounding the pivot H8, and which engages the other of the shoes. This forms a two part applying device, one part of which is pivoted on the anchor, and which has substantially equal action on the two shoes. The webs of the shoes are embraced between the lever 2 l4 and the head of the pivoted member 220. The body of the lever is cut away at 224, to clear the anchor.

The arrangement of Figure 4 differs from that just described mainly in the wedging or cam surface of thelug 226, formed on the member 226 and corresponding to lug 222. The curve of lug 222 is substantially on the arc of a circle and engages the end of the shoe with a substantially tangential thrust. The lug 226, on the other hand, engages the shoe web substantially at its outer edge and, since it swings about the anchor 208, has a considerable component urging the shoe downwardly in the brake in forward braking, thus tending to cause the heel of the shoe to engage the drum' slightly before the toe.

In'Figure 5, the lever 2 M has pivotally mounted thereon a thrust cam 228 in thrust engagement with the end of one shoe and having a tail portion guidingly engaging the anchor post 238.

Figure 6 shows a lever 230 corresponding to lever 2M having a portion bridging across below the anchor 208 and connected to the left-hand shoe by means such as a pivot 232. Above the anchor the lever 230 has a thrust pin 234 wedgingly engaging a lug 236 on a member 238 (shown in reverse in Figure 7) pivoted on the anchor 288 and which lug 236 is also in thrust engagement with the end of the right-hand shoe.

In Figures 8 and 9 a lever 240 (corresponding to the lever 2) has two thrust lugs 242 on opposite sides of the anchor, and also has a pin carrying a roller 244 riding in and supported by an inclined cam-slot 246 in a member 248 fixedly mounted on the anchor 208.

Figure 10 shows a floating lever 250 provided, on opposite sides of the anchor, with two thrust pins 252. The upper pin 252 is received in registering-,semi-circular notchesin the -:ends of the shoe webs,-.and the--lower pin 2521--has -wedging engagement with inclined. cam surfaces on the ends of the shoe webs.

In operation, force applied in tension on the cable 50 serves to spread the shoes apart to apply the brake. In Figure 1, inforward braking the spring 2I0 pulls at such. anan'gle iastohold the left-hand shoe I96 (the secondary shoe) against the anchor, while the lever 2I4 fulcrums on lug 2I6 engaging the left-hand-shoe I96 and lug 222 thrusts the right-hand shoe I96 (the primary shoe) against the drum. In reverse braking, the action is the same for the brief instant before the primary shoe has anyfrictional engagementwith the-. drum. =As soon-as thereiis such engagement, :however, and even before either shoe fully engages'the drum, the wiping action of the drum (rotatingcounter-clockwise) forces ;the .primary (right-hand) shoe back against the-anchor. -From there on the lever 2 I4 fulcrums on thepi-vot2l8, and lug 2I6 forces the secondary (left-hand) shoe away from the anchor and against the drum.

In t-hecase ofeEigurei, the action is substantiallythe same as gjust described, except thatthe heel of the primary shoe engages thedrum somewhat sooner. In Figure .5, in forward braking the applying lever acts as described above except that the thrust lug :228 .-engaging the primary shoe can turn onits pivot under the control of the .camming engagement of the tail portion riding-on the anchor 208,-so that its angle of thrust ,may be ,changed as desired at different stages of brake application. In reverse braking the action will be as previously described.

.Inthe, arrangement of Figure 6, the lever 230 fulcrums on pivot 232 in forward braking, the applying action :being by thrust lug v236 acting on the right-hand shoe; in reverse braking the pina234of the lever fulcrums slidably against lug .236, and pivot-232 acts to apply the brake. .In Figure 8 the lugs-242 apply the brake, the lower one'servi-ngas a fulcrum in -forward braking and the upper onein reversebraking. The action of the lever is controlled by the shape and inclination ofthe cam-slot 246. In.-Figure 10 the lever 250 fulcrums slidably :on they lower -lug.252 in forward braking, and pivots as a fulcrum on the upper-lug .252 in reverse braking.

While several illustrative embodiments have been described in detail, it is not my intention to limit thescope of the invention to those particular-embodiments, or otherwise than by the terms of the-appended claims. I

The present application is a division of my application No. 708,171, filed January 25, 1934.

I claim:

1. Brake mechanism. comprising friction means having adjacent separable ends, an anchor between said ends, a part pivoted on said anchor and having means operatively engaging one of said ends on one side of the anchor, and a floating lever pivoted to said part at said side of the anchorandyiormed to clear-said anchor and movable independently of .saidsanchor', rand having means operatively engaging the other of said :;.erids at the other side of the anchor.

2. Brake mechanism comprising friction means having adjacent separable ends, an anchor between said ends, apart pivoted on said anchor :and having meansioperatively engaging one of .said ends onione'side of the anchor, and a floating lever pivoted to the other of said ends at the other. side-. of the anchor and arranged to clear said anchor and having wedging engagement with saidjpart-for operating it.

3. Brake mechanism comprising, in combination with friction means having an anchor be- .tween 1 adjacent :separable aends an applying: .device .including -a :member .-pivotally mounted ion said anchor, a lever-.clea-ring-said .anchonand pivoted to-saidlmemberat oneisideof theanchor I and swinging ;parallel .to the .brakebeside cthe porting saidleverrand which is inthrust I engagementwith theother of said ends at the otherside of the anchor, said lever being formed between said :part .and the-pivotal connection with. said member with ianeopening zafiording clearance for said anchor.

5. Brake mechanism comprising, combination witha .backing plate carrying friction .means and having an ianchor projecting .between adjacent ends of the-friction means,- and= applying means having thrust}partsengagingsaid ends respectively on opposite :sides of @theaanchor and which means includesmovably connected parts, one of which-.is pivoted on theanchoriand .the other-of whichvis a.lever swinging :in the :space between thebacking plate and the. friction means.

6. Brake mechanism comprising separable shoes I having .an anchor between their ends, ran applying lever directly engaging one shoe on one side of the1anchor,-and ;a .partmounted on said anchor andhaving on .the' other -:side:of the :anchor means operated by said leverrand engaging the. otherashoe to] apply :it.

HAROLD G. AXTMANN. 

